The book grew out of Carnegie's experiences teaching adult education courses at the YMCA in New York City. Nearly all his students struggled with some kind of worry, and Carnegie set out to compile the tips they had used to conquer their anxiety.

We read through "How to Stop Worrying and Start Living" and highlighted the most practical and least banal advice that's stood the test of time. Read on to find out how to free yourself from everyday fears, so that you have time and energy left to accomplish the things that truly matter to you.

1. Ask yourself, 'What's the worst that can happen?'

First, ask yourself, "What's the worst that can happen?" Second, prepare to accept the worst. Third, figure out how to improve upon the worst, should it come to pass.

The technique is based on an anecdote from Willis Carrier, founder of the modern air-conditioning industry. As a young man, Carrier found that a new service his company provided wasn't as effective as he'd hoped.

Carrier realized that the worst that could happen was that his company would lose $20,000. He then accepted it: The company could qualify the loss as the cost of researching a new strategy. Finally, he figured out how to improve the situation: If the company bought $5,000 worth of new equipment, they could resolve the issue. Ultimately, that's exactly what they did, and they ended up making $15,000 because the additional equipment proved so effective.

2. Gather all the facts in an objective way.

Carnegie suggests two ways to go about collecting facts objectively. You can pretend that you're gathering this data for someone else, so you're less emotionally invested in what you find.

Or you can pretend that you're a lawyer who is preparing to argue the other side of the issue — so you gather all the facts against yourself. Write down the facts on both sides of the case and you'll generally get a clearer picture of the truth.

3. Generate potential solutions to the problem.

This strategy is especially useful for eliminating business worries. It's based on wisdom from Leon Shimkin, who was general manager and then owner of Simon and Schuster.

Shimkin told Carnegie he cut meeting times by 75% by telling his associates that, every time they wanted to present a problem at a meeting, they had to first submit a memorandum answering four questions: What is the problem? What is the cause of the problem? What are all possible solutions of the problem? What solution do you suggest?

According to Shimkin, once he instituted this new system, his associates rarely came to him with their concerns.

4. Remember the law of averages.

The law of averages refers to the probability of a specific event occurring — and you should consult the law to find out if it's worth fretting. Chances are good that whatever you're worried about isn't likely to transpire.

Carnegie writes that the US Navy employed the law of averages in order to boost sailors' morale. Sailors who were assigned to high-octane tankers were initially worried that they would be blown up when the tank exploded. So the Navy provided them with exact figures: Of the 100 tanks that were hit by torpedoes, 60 stayed afloat and only five sank in less than 10 minutes, leaving time to get off the ship.

REUTERS/Brendan McDermid

5. Place stop-loss orders on your worries.

This strategy is based on a principle in stock trading. One investor told Carnegie he set a stop-loss order on every market commitment he made.

Here's how it works: Say you buy a stock that sells for 100 dollars a share and set a stop-loss order for 90 dollars a share. As soon as that stock dips to 90 dollars a share, you sell it — no questions asked.

You can use this principle in everyday life. For example, Carnegie once wanted to be a novelist, but after two years of toiling away without much success, he decided to cut his losses and go back to teaching and nonfiction writing.

6. Live for the day.

"One of the most tragic things I know about human nature," Carnegie writes, "is that all of us tend to put off living."

In other words, we're so consumed with worrying about what we've already done wrong in the past and what might go wrong in the future. Instead, Carnegie advocates living in what he calls "day-tight compartments" that don't allow past or future concerns to seep in.

Carnegie gives an example of how this technique helped save one man's life. After opening his own business, Edward Evans experienced a series of disasters: He lent money to a friend and the friend went bankrupt. The bank where he held all his money collapsed and he went $16,000 into debt.

Evans fell ill and a doctor told him he had just two weeks to live. "No use now to struggle or worry," Evans remembered thinking. Finally, he was able to sleep, eat, and even go back to work.

Restored to health, a few years later, he was president of the Evans Products Company, which produced equipment for loading and shipping automobiles.

7. Keep busy.

"It is utterly impossible for any human mind, no matter how brilliant, to think of more than one thing at any given time," Carnegie writes. The same logic applies in the domain of emotions, he said — you can't be ecstatic and plagued by fear at the exact same moment.

Therefore, in order to crowd out worry, occupy your mind and body with another activity.

Carnegie cites the example of Tremper Longman, a businessman who cured his own insomnia by keeping his schedule jam-packed.

Longman was treasurer of the Crown Fruit and Extract Company, and sales dropped suddenly when the big ice cream companies started buying their strawberries in barrels instead of the gallon tins that Crown sold. Even when Longman came up with a potential solution to the problem, he couldn’t stop worrying and said he was headed for a nervous breakdown.

Desperate for a solution, he decided to absorb himself fully in his business problems, working 16-hour days. By the time he got home at midnight, he was so exhausted that he had neither the time nor energy to worry.

Long after Longman went back to working seven-hour days, he said, he had beat the habit of worry and the bouts of insomnia for good.

8. Accept the inevitable.

If there's any chance you can change a situation by acting differently, Carnegie tells readers to go for it.

But if circumstances are obviously unalterable, worrying will only change you for the worse, he says. It's an idea he heard from multiple business executives he interviewed.

Here's JC Penney, founder of the retail chain by the same name: "I wouldn't worry if I lost every dollar I have because I don't see what is to be gained by worrying. I do the best job I possibly can; and leave the results in the laps of the gods."

9. Act happy to feel happy.

Unfortunately, we can't control much of what we feel. But we have near-complete control over what we do. And changing our behavior often affects our emotions in turn.

You can try it right now: Smile and see if you still feel despondent.

"It is physically impossible to remain blue or depressed while you are acting out the symptoms of being radiantly happy!" Carnegie writes.

10. Give up resentment.

There's little point in stewing over old grievances and harboring grudges against people, Carnegie says. Instead, it's healthier to just move on.

But how?

"One sure way to forgive and forget our enemies is to become absorbed in some cause infinitely bigger than ourselves," Carnegie wrote.

That's what Abraham Lincoln reportedly did. According to William Herndon’s biography of the US president, "If a man had maligned him or been guilty of personal ill-treatment, and was the fittest man for the place, Lincoln would give him that place."

In other words, Lincoln's primary cause was getting the political job done; he didn't have time to let personal injuries get in the way.

11. Understand why people criticize.

"When you are kicked and criticized," Carnegie writes, "remember that it is often done because it gives the kicker a feeling of importance."

That idea is evidenced by an anecdote Carnegie shares about the Prince of Wales. When the prince was about 14 years old and attending a naval academy, one of the naval officers found him crying. When he asked the prince why, the prince replied that the naval cadets had been kicking him.

The commodore of the academy asked the cadets to explain why they had kicked the prince. Apparently, the cadets had wanted to be able to say they had kicked the king.